Light extraction improvement in GaAs light-emitting diodes for teraherz upconversion imaging

Area of Science:

• Photonics
• Optoelectronics
• Materials Science

Background:

• Upconversion pixelless imaging offers advantages over electrical readout for infrared/terahertz applications.
• Low external quantum efficiency of LEDs limits overall upconversion efficiency and practical use.
• High-speed, high-resolution imaging is hindered by current upconversion efficiency limitations.

Purpose of the Study:

• To enhance the quantum efficiency of LEDs for improved upconversion imaging.
• To investigate the impact of surface microstructures on LED luminescence characteristics.
• To provide a pathway for optimizing upconversion pixelless photon imaging technology.

Main Methods:

• Fabrication and characterization of LEDs with varying surface microstructures.
• Systematic study of luminescence properties at low temperatures, including electroluminescence efficiency (ELE), spectrum, and uniformity.
• Experimental validation of efficiency improvements compared to planar structures.

Main Results:

• Designed LED structures achieved up to 55% higher electroluminescence efficiency than planar structures at low temperature and low current.
• The enhanced structures exhibited good monochromaticity and luminous uniformity.
• Surface microstructure design was shown to effectively improve external quantum efficiency.

Conclusions:

• Surface microstructures offer a viable method to significantly boost LED quantum efficiency.
• This approach provides a theoretical and experimental basis for optimizing upconversion imaging devices.
• The findings are crucial for advancing high-resolution, high-speed photon-type imaging in the infrared/terahertz spectrum.